| 摘要 |
PROBLEM TO BE SOLVED: To hold a mesa angle fixedly so that the dimension and shape of a mesa can be accurately controlled by forming the projected mesa for a base plate while forming at least one recessed mesa in the top of the base plate. SOLUTION: A mask material film is formed on a single crystal silicon base plate 12, and a first mesa mask 14 is formed on the mask material 11 to perform anisotropic etching to the base plate 12 and form a first mesa 101 having a mesa angleθ1. Next, the mask material film is formed on the peripheral edge portion of the top of the first mesa 101 to form a second mesa mask 16 and thereafter the anisotropic etching is performed in the first mesa 101 to form a second mesa 102 having a mesa angleθ2. Thus, the bottom area of the first mesa 101 is prevented from being reduced with several times the etching speed of etching the crystal orientation surface 100 of the top B of the first mesa 101 and the crystal orientation surface 100 of the periphery of a diaphragm 10 to avoid the reduction of mesa dimension. Thus, the mesa anglesθ1,θ2 can be held at fixed one, and the mesa dimension and shape can be accurately easily controlled.
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